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Cybersecurity › Network Security

Access Control Lists

18 Controls
Access Control Lists (ACLs)

Define and enforce network traffic rules at various network layers.

  • Follow deny-by-default — only allow explicitly permitted traffic
  • Place most specific rules first; order matters
  • Log denied traffic for threat detection
  • Review and audit ACLs quarterly
# Cisco ACL — restrict inter-VLAN traffic
access-list 100 permit tcp 10.10.10.0 0.0.0.255 10.20.20.0 0.0.0.255 eq 443
access-list 100 permit tcp 10.10.10.0 0.0.0.255 10.20.20.0 0.0.0.255 eq 22
access-list 100 deny   ip  10.10.10.0 0.0.0.255 10.20.20.0 0.0.0.255
access-list 100 permit ip  any any